Ba Doping Research Articles

Bond engineering: weakening Ru–O covalency for efficient and stable water oxidation in acidic solutions

The persistent stability of ruthenium dioxide (RuO2) in acidic oxygen evolution reactions (OER) is compromised by the involvement of lattice oxygen (LO) and metal dissolution during the OER process. Heteroatom doping has been recognized as a viable strategy to foster the stability of RuO2 for acidic OER applications. This study presented an ion that does not readily gain or lose electrons, Ba2+, into RuO2 (Ba–RuO2) nanosheet (NS) catalyst that increased the number of exposed active sites, achieving a current density of 10 mA/cm2 with an overpotential of only 229 mV and sustaining this output for over 250 h. According to density functional theory (DFT) and X-ray absorption spectroscopy, Ba doping resulted in a longer Ru–O bond length, which in turn diminished the covalency of the bond. This alteration curtailed the involvement of LO and the dissolution of ruthenium (Ru), thereby markedly improving the durability of the catalyst over extended periods. Additionally, attenuated total reflectance-surface enhanced infrared absorption spectroscopy analysis substantiated that the OER mechanism shifted from a LO-mediated pathway to an adsorbate evolution pathway due to Ba doping, thereby circumventing Ru over-oxidation and further enhancing the stability of RuO2. Furthermore, DFT findings uncovered that Ba doping optimizes the adsorption energy of intermediates, thus enhancing the OER activity in acidic environments. This study offers a potent strategy to guide future developments on Ru-based oxide catalysts’ stability in an acidic environment.

Optical and electronic properties of RENiO3 doped with alkali earth metals (Be, Mg, Ca, Sr and Ba): Combining first principles calculations and machine learning

The perovskite rare earth nickelate (RENiO3) has attracted significant attention owing to its peculiar physical properties and promising potential for diverse applications. It is reported that introducing H or Li might change the electronic and optical properties of RENiO3. However, little is known about multi-electrons doping in RENiO3. In this study, the bandgaps, optical and electronic properties were investigated in RENiO3 with alkaline earth metal (AEM) elements (Be, Mg, Ca, Sr and Ba) doping. For the atomic configurations of doped RENiO3, the interstitial sites of RENiO3 are more likely to be occupied by Be, Mg and Ca atoms, whereas Sr and Ba atoms tend to replace RE atoms in RENiO3. The band gap of RENiO3 decreases after AEM doping. Moreover, the machine learning results found that the formation energy of the AEM, the relative atomic mass of the AEM, and the doping position significantly influence the band gap. Furthermore, the infrared light blocking capability, the visible light transmission, and the electronic conductivity are enhanced in AEM doped RENiO3. This study may contribute to the experimental modulation of the optical and electronic properties of RENiO3 through AEM doping.

In situ construction of one-dimensional structures induced by Ba doping in Al2O3-TiO2 ceramics derived from quenched powders

In this work, we propose a strategy for in situ construction of rod-like grains in Al2O3-TiO2 ceramics through Ba doping. Ba-doped Al2O3-13 wt% TiO2 composite powder was initially synthesized using combustion synthesis-air atomization, where feedstocks were melted by the Al-O2 combustion reaction and subsequently atomized and rapidly cooled in air, producing quenched powders rich in metastable phases. Upon heat treatment at 1100℃, the metastable phases transformed into stable forms, accompanied by phase separation and solid solution precipitation. Notably, Ba doping induced the formation of rod-like hollandite grains with preferential growth along the [001] direction. Bulk ceramics were prepared through pressureless sintering, and the sample sintered at 1350℃ exhibited a hardness of 14.14±0.61GPa and a fracture toughness of 5.17±0.49MPa∙m1/2. The toughening behavior of rod-like grains, including crack deflection and pull-out/bridging effects, was observed. This study provides insights into the evolution of quenched oxides and the design of ceramic microstructures.

High thermally stable and efficient rare-earth celsian by phase transformation of Ba2+-Exchanged SOD zeolite

The white LEDs with high performance and excellent luminous quality is of high importance for developing the current lighting industry, and high thermally stable blue phosphors play a critical role in the preparation of white LEDs. Herein, we reported a facile way to obtain highly efficient blue Eu2+-doped celsian phosphor with excellent thermal stability by a phase transformation of Ba2+-exchanged SOD Zeolite strategy. The structure of phosphors changed from nepheline to celsian with the doping of Ba2+, and the maximum emission intensity blue-shifts from 550 nm to 450 nm under the excitation of 370 nm. The PLQY is determined to be 56 %, 96 % and 82 % for the phosphor with Ba2+ doping concentration being 0, 1.49 and 1.86, respectively, and the luminescence intensity at 423 K is can be 80 %, 102 % and 93 % of its intensity at room temperature. Finally, the package of the LED device based on our yellow and blue phosphors together with the commercial red CaAlSiN3:Eu2+ phosphor is constructed to show warm white light with the CCT of 3705 K and a high CRI of 97.7. This study provides a facile way for obtaining satisfactory phosphors for high-quality lighting.

Electrical transport properties of topographically demorphed films of La1-xBaxMnO3 grown on (00l)-oriented LaAlO3 substrate via spin-coating method

Herein, the crystal structure, valence, and electrical transport properties of La1-xBaxMnO3 films were examined by preparing La1-xBaxMnO3 films with varying Ba content (x = 0.22, 0.24, 0.26, 0.28) on LaAlO3 substrates using the sol-gel spin coating technique. The La1-xBaxMnO3 films prepared in the study exhibit topographically demorphed and non-dense characteristics in the microstructure, which is mainly caused by the Volmer-Weber growth mode of the films and the volatilization of organic matter during the sol-gel sintering process for films preparation. The increase of Ba doping leads to MnO6 deformation, decrease in grain boundary scattering, increase in Mn4+ ion content, and enhancement of both the double exchange mechanism and the Jahn-Teller effect. The four-probe results showed that the peak resistivity of the films decreased significantly with the increase in Ba2+ doping, and the metal-insulator transition temperature (Tp) shifted to higher temperatures. Peak temperature coefficient of resistivity (TCR) corresponding temperature (Tk) increased from 283.05 K (x = 0.22) to 309.31 K (x = 0.28), which was consistent with the trend of Tp; the peak value of TCR decreased with the increase of Ba doping. When x = 0.24, the Tk of the La1-xBaxMnO3 films reach room temperature (294.25 K) with TCR = 9.01 % K−1. In conclusion, the electrical properties of La1-xBaxMnO3 can be optimized by varying the amount of Ba doping to obtain La1-xBaxMnO3 films with room-temperature Tk and higher TCR values, providing reasonable data support and theoretical explanation for the Ba doping mechanism.

Modulating the structural and electrical properties of SrFeO3–δ by a-site alkali metal ion doping

The electrical properties of perovskite structured SrFeO3–δ can be modulated by A site doping. The present work focuses on the influence of concentration and ionic radii of alkali metal cation on the structural and electrical properties of Sr1–xAxFeO3–δ (A = Ca, Ba and x = 0, 0.25, 0.50, 0.75). The x-ray diffraction studies confirm the phase change from cubic to orthorhombic with Ca content while orthorhombic to cubic structural translation was observed with Ba concentration. A lattice contraction and expansion were observed for doping depending on the ionic radii of dopant cation. The x-ray photoelectron spectroscopy results indicate the presence of Fe in mixed valence state of +2, +3, +4 state and adsorbed oxygen content was found to be higher upon Ba doping than that of Ca. A maximum conductivity of 1.82 × 10−3 S cm−1 (x = 0.25) and 5.31 × 10−3 S cm−1 (x = 0.5) was observed at 800 °C for Ca and Ba doped samples, respectively, one order higher than the base SrFeO3–δ .Thus, our results emphasise the importance of dopant addition on tailoring the electrode properties for SOFC application.

Research on the method of improving carbon storage capacity of a new low calcium CO2 storage binder: Based on the recycling of heavy metal Ba ions

The novel low calcium CO2 storage binder (LCCSB) containing α-CS, C3S2 and C2AS as the primary minerals shows promise as a carbon fixation material, but exhibits low carbonation activity. This study aims to enhance the carbonation activity of LCCSB through barium (Ba) doping, investigate the impact of Ba doping on its carbonation behavior, and elucidate its mechanism. Density functional theory (DFT) simulation, scanning electron microscope test and X-ray diffraction results indicate that Ba ions preferentially substitute Ca atoms within α-CS, followed by Ca sites in C3S2, with a maximum solid solubility of 1mol%. Following Ba ion solid solution into LCCSB, there is an increase in carbonation reaction products along with elevated levels of calcite and aragonite. Additionally, small particles are formed to fill mineral matrix and pores leading to increased porosity and enhanced hardening strength. DFT calculations reveal that Ba ion doping reduces the total bond sequence density TBOD of the LCCSB system while weakening the bond strength of Ca–O bonds thereby accelerating the dissolution of Ca ions. Furthermore, average bond length, volume and distortion index of Ca–O polyhedra increase after Ba ion doping indicating structural distortion resulting in more active sites for potential high carbonation reactivity. This study presents a new research approach for achieving high carbonation activity in LCCSB preparation while also offering insights into the potential for clarifying the carbonation mechanism based on ion-doped LCCSB which could lead to improved environmental and economic benefits for CO2 storage within the cement industry.

Effects of Ba doping on the structural, magnetic and microwave absorption properties for LaMnO3 perovskites

Effects of Ba doping on the structural, magnetic and microwave absorption properties for LaMnO3 perovskites

Exploring the physical properties of pristine γ-In2S3 and its influence on Ba doping for photocatalytic degradation of 2,4-D herbicide

In this work, pristine γ-In2S3 nanoribbons were synthesized using a facile solution process and uniquely doped with Ba for the first time. XRD and Raman spectroscopy confirmed the formation of pure-phase γ-In2S3 and successful Ba doping. XPS further validated the presence of Ba 3d core level with In 3d and S 2p after the inclusion of Ba. FESEM and HRTEM images showed the formation of nanoribbons, with the width increasing from 60 to 100 nm after doping. The anticipated stoichiometry of In and S, with approximately 2 atomic % of Ba, was confirmed by EDS. After Ba-doping, the bandgap was narrowed from 3.66 eV to 3.03 eV, and the charge carrier recombination was substantially reduced, as witnessed by PL and EIS. The potential of pristine γ-In2S3 and Ba-doped γ-In2S3 as new photocatalysts was highlighted in this study, exploring their applicability for the photodegradation of the stubborn herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). The materials demonstrated impressive performances, achieving degradation efficiencies of 77.08 % and 94.15 % before and after doping, respectively, within 210 min. The scavenging tests revealed a significant contribution of O2•− and •OH for 2,4-D degradation using Ba-doped γ-In2S3 photocatalyst. Besides photocatalysts used in this study demonstrated excellent stability after four cycles. These findings suggest a promising approach for developing cost-effective semiconductors to remove persistent herbicides.

Emergence of Perovskite and Hashemite-type phases in chromium doped (Ba0.90Sr0.10)(Fe1-xCrx)O3±δ oxides: Formation, Rietveld refinement and Raman spectra

Perovskite- and Hashemite-type oxides are relevant due to their applications as oxidizing agent, photocatalyst, nutrient, fuel cells, gas sensors, batteries materials. An attempt has been made here to synthesize (Ba0.90Sr0.10)(Fe1-xCrx)O3±δ(x = 0 – 1.0) and characterized with regards to structure and Raman vibrations. It depicts (a) pure cubic (Ba0.90Sr0.10)FeO3-δ phase, (b) cubic+orthorhombic, and (c) single orthorhombic (Ba0.90Sr0.10)CrO4 phase for x = 0–0.10, 0.20 – 0.80, and 1.0, respectively. It exhibits (i) decrease of cubic lattice parameter (ac)as 4.020 – 3.926 Å, (ii) expansion of orthorhombic unit cell, (iii) complete appearance of chromium in 6+ state for x = 1.0, and (iv) decrease of bond length and angle both with chromium. The bond lengths corresponding to Ba/Sr-O ∼ 2.84 Å, Fe-O ∼2.04 Å and Ba/Sr-O1 ∼ 3.227 Å, Ba/Sr-O2 ∼ 2.893 Å, Ba/Sr-O3 ∼2.859 Å have been derived for cubic (x = 0) as well as orthorhombic structure (x = 1.0), respectively. The bond angles e.g., Cr-O1-Cr ∼ 129°, Cr-O2-Cr ∼ 104.3° and Cr-O3-Cr ∼ 83.3° have been found for x = 1.0. Moreover, the bond Cr-O1 is compressed and Cr-O2 is more stretched than Cr-O3 bond. The morphology has also been changed to bigger size (nm) and shows different nature with chromium content. Raman spectra for Hashemite-type (Ba0.90Sr0.10)CrO4 reveal bands at ∼350, 360, 401, 425, 861, 886 and 904 cm−1 and arise due to symmetric (υ1, υ2) and antisymmetric (υ3, υ4) bending/ stretching mode. The present findings suggest potential applications of (Ba0.90Sr0.10)(Fe1-xCrx)O3±δ oxides.

Bandgap Energy of Ion‐Doped LaMnO3 Nanoparticles

Based on the s‐d model combined with Green's function technique, the magnetization and the bandgap energy of ion‐doped nanoparticles at La sites are calculated. Due to the change of the valency of Mn ions, from to , as well as the difference between the ionic radii of the doping and host ions, the exchange interaction is modified which allows a tuning of the magnetization and the bandgap energy. For nanoparticles, the bandgap is decreased by Ag and Ba doping, whereas it is increased by K and Sr doping. Macroscopic quantities such as the magnetization and the bandgap energy are directly related to microscopic parameters of the model. The simulations are qualitatively in good agreement with the experimental data.

Application of lattice expansion effect in SrCoO3 based cathodes by Ba doping with elevated electrochemical performances for low-temperature solid oxide fuel cells

Developing excellent-performance cathode materials is an inevitable and challenging obstacle in the process of developing practical solid oxide fuel cells, especially in low temperature range. In this paper, we introduce barium into the premium SrCoO3-based cathodes and research its consequent effect in the oxygen reduction reaction process. It is observed that the barium dopant could expand the lattice, produce more oxygen vacancies and at some extent reduce the thermal expansion coefficient of parent perovskite, which results from the expanded free space for oxygen migration and weakened Co–O bond by Ba doping. The polarization resistances of single cells with Sr1-xBaxCo0.8Sc0.1Nb0.05Ti0.05O3-δ cathodes (x = 0, 0.2 and 0.5, defined as SCSNTi, SB0.2CSNTi and SB0.5CSNTi, correspondingly) are 0.038, 0.025 and 0.016 Ω cm2 at 600 °C, respectively, and corresponding peak power density of 0.852, 1.054 and 1.217 W cm−2. The SB0.5CSNTi cathode is selected and it stably operates for 200 h at 550 °C. And it also exhibits excellent performance when CH4 is used as fuel and good stability for 100 h at 600 °C. First principle calculations prove that the Ba doping effectively reduces the oxygen vacancy formation energy and oxygen migration barrier. This work proves that the lattice expansion effect is an effective strategy for accelerating the oxygen exchange rate and designing high-performance cathode materials.

High‐Performance CaMg2Bi2‐Based Thermoelectric Materials Driven by Lattice Softening and Orbital Alignment via Cadmium Doping

AbstractZintl compounds such as n‐type Mg3(Sb,Bi)2 show promising thermoelectric applications benefiting from their high valley degeneracy and low lattice thermal conductivity. However, the heavier p‐type AMg2X2 (A = Ca, and Yb; X = Bi and Sb) Zintl counterparts even exhibit a higher κlat due to strong chemical bonding. Reducing κlat of AMg2X2 is an important route for improving thermoelectric performance. Herein, it is found that Cd doping at the Mg site in CaMg2Bi2 can weaken intralayer covalent bonds and soften acoustic phonons, as well as fill the optical phonon gap. These effects result in large atomic displacement, low phonon group velocity, and strong lattice vibration anharmonicity. Doping 10% Cd leads to a reduction of 56% in the κlat of CaMg2Bi2. Moreover, Cd doping promotes orbital alignment and thus increases the density‐of‐states effective mass and Seebeck coefficient. Eventually, in conjunction with carrier concentration optimization by Na doping and band structure engineering by Ba doping, a high ZT of ≈1.3 at 873 K in (Ca0.85Ba0.15)0.995Na0.005Mg1.85Cd0.15Bi2 sample is realized. This work highlights the significant role of manipulating chemical bonding in suppressing phonon propagation of semiconductors.

Ba Doping Effects on the Superconductivity and Electronic Structure of K2Mo3As3

Ba Doping Effects on the Superconductivity and Electronic Structure of K2Mo3As3

Synthesis and Comprehensive Analytical Study of β-Li3PS4 Stabilization by Ca- and Ba-Codoped Li3PS4.

Sulfide-based solid electrolytes with high Li+ conductivity, such as Li3PS4, are key materials for the realization of all-solid-state Li+ batteries. One approach to achieving high Li+ conductivity is to combine crystalline-phase stabilization at high temperatures with the introduction of defects at room temperature. In this work, this approach was verified by codoping Li3PS4 with two kinds of divalent cations. The resulting structural changes were comprehensively investigated both experimentally and computationally. The high-temperature β-Li3PS4 phase of Li3PS4 could be stabilized at room temperature by adjusting the amount of Ca or Ba doping. The synthesized samples doped with divalent cations were found to have conductivities about 2 orders of magnitude higher than that of the γ-Li3PS4 phase at room temperature. The resultant Li+ conductivity at room temperature was also higher than that expected from interpolation of results for nondoped β-Li3PS4. It is believed that the structural changes produced by the divalent cation doping contribute to this increase in conductivity. The stability of the β-Li3PS4 phase with divalent cation doping was also demonstrated using density-functional-theory calculations for models with equivalent compositions to the synthesized samples. The Li+ positions obtained by structural optimization calculations showed the presence of diverse and disordered Li sites in the Ca-doped lattice. Such structural changes can contribute to cascade processes involving Li+ collisions, referred to as the "billiard-ball" mechanism, which cannot occur in nondoped β-Li3PS4. This series of experiments involving the synthesis and analyses of β-Li3PS4 with divalent cation doping provides a way to enhance Li+ conductivity through structural modification and optimization.

A DFT study of (La2O3)n clusters and effect of Ba, Y and Hf doping for their optoelectronic applications

( La 2 O 3 ) n (n=1-5) clusters have been computationally studied using DFT and TDDFT with B3LYP functional under hybrid GGA approximation and LANL2DZ basis set. The doping effect of various elements like Ba, Y and Hf on the structural, electronic and non-linear optical (NLO) properties of ( La 2 O 3 ) n clusters has been studied for finding their optoelectronic applications. Different optimised geometries of ( La 2 O 3 ) n and Ba, Y and Hf doped ( La 2 O 3 ) n clusters have been obtained. HOMO-LUMO gap ( Δ E ) and chemical hardness (τ) of ( La 2 O 3 ) n clusters decreases significantly with doping of Ba, Y and Hf atoms making these clusters very reactive. Refractive index and the absorption in UV–VIS region of electromagnetic spectra of Ba, Y and Hf doped ( La 2 O 3 ) n clusters increases as compared to ( La 2 O 3 ) n clusters making these clusters suitable to be used as additives in the manufacturing of various types of glasses. Also, dielectric constant (ϵ) of Ba, Y and Hf doped ( La 2 O 3 ) n clusters increases finding their applications to be used in the oxide layer of MOSFETs.

Influence of electronic transport mechanism optimization on the thermoelectric properties of ZnO based functional ceramics

ZnO is one of the most promising mid-high temperature thermoelectric materials because of low cost, easy preparation and favorable chemical stability. Herein, the influence mechanism of Alkaline earth metal Ba doping on the thermoelectric properties of ZnO was studied. It is found that Ba doping can effectively improve the carrier mobility and electrical conductivity for that Ba doping can shorten the Zn–O bond and enhance the overlap and hybridization of electron orbitals. The electronic density of states of Zn and O is significantly enhanced. The highest power factor of ∼7.95 μWcm−1K−2 was obtained at 873 K, which is ∼1.4 times higher than that of the undoped sample. Due to the decrease of Young’s modulus caused by Ba doping and the enhancement of phonon scattering of heavy element, the thermal conductivity decreases obviously in the whole temperature range. Ba doping enhanced the effect of phonon glass-electron crystal, and the ZT value of ∼0.345 was obtained at 873 K, which is ∼3.52 times as that of the pristine ZnO. The results indicated that alkaline earth metal doping is an effective way to improve the thermoelectric properties of ZnO functional materials.

Structure evolution and energy band modulation in Ba-doped BiFeO3 thin films

Bi1−xBaxFeO3 (BBFO, x = 0, 0.03, 0.1) thin films were epitaxially grown on SrRuO3-buffered SrTiO3 (001) substrates by pulsed laser deposition. With increasing Ba content, the BBFO thin films show significantly reduced leakage currents but suppressed ferroelectric polarization. X-ray diffraction reciprocal space mappings and Raman spectra indicate a structural evolution from a rhombohedral-like to tetragonal-like phase in the BBFO thin films. Optical absorption and photoelectron spectroscopy measurements demonstrate a modulation of energy band structures in the BBFO thin films. With A-site Ba acceptor doping, the BBFO thin films exhibit a blue-shift of optical bandgap and an increase in work function. The energy positions of conduction and valence bands of the BBFO thin films have been modulated, and the Fermi level shifts down to the center of the forbidden band, but acceptor-doped BFO thin films still show n-type conduction. The presence of extra oxygen vacancies by acceptor doping is supposed to make contribution to conduction behavior. This study provides a method to manipulate the functional properties and gives insights into the physics of Ba doping in BFO thin films.

Probing the impact of Ba on properties of ZnO at the nanoscale: optical, dielectric and antibacterial activity evolution

The sol–gel dip coating technique was used to manufacture undoped and Barium doped zinc oxide thin films. Doping is extensively used to refine semiconductor properties. Without and with varying ratios of Ba 1–9 wt% dopant, ZnO thin films have been manufactured. The effect of Ba on the dielectric, structural, antibacterial, optical and morphological characteristics of ZnO was investigated. The optical properties demonstrate that the bandgap of the pure ZnO thin film is higher than that of Ba-doped ZnO films, which is beneficial for improving solar cell performance. According to the XRD data, all films of ZnO have hexagonal wurtzite structures According to XRD structural analysis; the incorporation of Ba lowers the crystallinity of ZnO thin films by reducing the crystallite size. The Ba doping changes the surface roughness and morphology. The hopping process defines the dielectric characteristics that follow Koop’s theory as well as the Maxwell–Wagner model. A lower dielectric constant makes it ideal for high-frequency devices. These films exhibit ferromagnetism. Barium-doped zinc oxide photocatalyst could successfully decompose methylene blue dye by making it suitable for wastewater treatment. Ba doping effectively kills both gram-negative and gram-positive bacteria. They have antimicrobial applications in the food industry and biomedicine.

Effect of zinc and magnesium ion doping on leakage current behavior of Ba0.6Sr0.4TiO3 thin film.

We report an in-depth analysis of the carrier conduction mechanisms in multilayer doped Ba0.6Sr0.4TiO3 films, which offers a significant new message for reducing the leakage current. First, Ba0.6Sr0.4TiO3 (BST) sol, Ba0.6Sr0.4Ti0.99Zn0.01O3 (ZBST) sol, and Ba0.6Sr0.4Ti0.99Mg0.01O3 (MBST) sol were prepared using the sol-gel method. Then, BST, ZBST, MBST, and binary alternating-structure Ba0.6Sr0.4Ti0.99Zn0.01O3/Ba0.6Sr0.4Ti0.99Mg0.01O3/Ba0.6Sr0.4Ti0.99Zn0.01O3 (ZMZ) thin films were designed and prepared. The effects of single-component doping and binary alternating doping on the interface barrier height and trap barrier height of the Ba0.6Sr0.4TiO3 thin films were studied. The results showed that the interface barrier height of ZMZ thin films is 0.55 eV, and the interface barrier height of BST thin films is 0.53 eV. Compared with the ZBST and MBST thin films, the change in the interface barrier height of the ZMZ film was not obvious. The trap barrier height of the ZMZ thin film is 0.17 eV, and the trap potential barrier height of the BST thin film is 0.12 eV. The trap barrier heights of ZBST thin films and MBST thin films are 0.15 eV and 0.16 eV, respectively. The enhancement of the trap barrier height may be related to the weakening of the trap and donor effects caused by oxygen vacancy defects. The energy band diagram shows the relationship between the oxygen vacancy defects, interface barrier height, and trap barrier height.